材料期刊网

INTERFACE MORPHOLOGIES AND MICROSTRUCTURES DURING DENDRITE-TO-CELL TRANSITION AT HIGH GROWTH RATE

LI Jianguo MAO Xiemin FU Hengzhi National Laboratory of solidification Technology , Northwestern Polytechnical University , Xi'an , China Lecturer.Faculty No.403 , Northwestern Polytechnical University , Xi'an 710072 , China

金属学报(英文版)

The interface morphologies and microstruetures of the directionally solidified Ni-5wt-% Cu alloy during dendrite-to-cell transition at high growth rates have been investigated with a newly developed apparatus for unidirectional solidification with the temperature gradient at the solid/liquid interface higher than 1000 K/cm.The results show that in the vicinity of dendrite-to-cell transition point,the well developed sidebranches become shrivelled with the increase of growth rate and disappear at the dendrite-to-cell transition,and the primary spacing decreases simultaneously.Moreover,the length of mushy zone decreases greatly dur- ing the dendrite-to-cell transition.Cells obtained at high growth rates have very similar morphologies to those at low growth rates,but with much smaller cell spacings and unsmoothed cell walls which may be attributed to the different stability conditions of the cell walls at low and high growth rates respectively.

关键词: cellular growth , null , null , null , null

STATISTICAL EVALUATION OF CRITICAL INCLUSION FACTOR FOR SECONDARY RECRYSTALLIZATON IN 3%Si STEEL Lecturer,Department of Materials Engineering,Southwestern Jiaotong University,Chengdu 610031,China

LI Shuchen Southwestern Jiaotong University , Chengdu , ChinaCHEN Mengzhe KE Jun University of Science and Technology Beijing , Beijing , China

金属学报(英文版)

On the basis of statistical data of MnS in the conventional 3% Si steel sheeets after various annealing processes,the critical inclusion factor has been evaluated to be 20 mm~(-1).The inhi- bition of MnS to grain growth has been exactly described.

关键词: 3%Si steel , null , null

CORRELATION BETWEEN STRESS COMPONENTS AND STRESS CORROSION CRACKS IN BRASS Lecturer,Department of Materials Physics,University of Science and Technology Beijing,Beijing 100083,China

QIAO Lijie LIU Rui XIAO Jimei University of Science and Technology Beijing , Beijing , China

金属学报(英文版)

The effects of stress components on nucleation sites and propagation directions of stress cor- rosion cracks in brass were investigated with specimens under mode Ⅱ and mode Ⅲ loadings. The results indicated that under mode Ⅱ loading,stress corrosion cracks nucleated on the site with maximum normal stress component and propagated along the plane perpendieular to the maximum normal stress,under mode Ⅲ loading,the stress corrosion crack was not evident on the 45°plane due to the general corrosion in aqueous solution with high NH_4OH concentra- tion,while stress corroded in aqueous solution with low NH_4OH concentration, numerous cracks with spacings of 10—150μm were found on the 45°plane with maximum normal stress and no stress corrosion cracks was observed on the plane with maximum shear stress.

关键词: stress corrosion cracking , null , null , null

K403高温合金缺损叶片的粉末冶金法修复

张杰 , 翟玉春 , 王茂才

稀有金属材料与工程

采用粉末冶金修复工艺(China Powder Metallurgy,CPM),利用2种分别混有微量硼合金和纳米镍粉的镍基高温合金粉末对K403缺损叶片进行修复再制造.采用X射线衍射、扫描电子显微镜(SEM)、EDX能谱和电子探针(EPMA)对叶片修复区的相组成、宏观形貌及微观组织进行分析;同时对修复区致密化和界面连接机理进行初步探讨.结果表明,选用合适的修复粉末,用CPM方法能够将缺损的叶片再制造成原有形状与尺寸;混合硼合金的修复粉末对K403合金的修复效果较好;硼元素的扩散对修复区致密化和界面连接起重要作用,期间发生的反应为NimBn+(Cr,W)→γ+(Cr2,W)B2;经计算,在CPM工艺条件下,界面区的硼浓度可以降低至共晶浓度以下.

关键词: 粉末冶金 , 修复工艺 , K403高温合金 , 叶片

403Nb叶片钢热压缩变形研究

王立民 , 刘宁 , 刘正东 , 杨钢 , 张秀丽

钢铁

为403Nb叶片钢实现热连轧组织性能预报系统提供数据,采用Gleeble-3500热模拟试验机,对403Nb进行了热压缩试验.根据试验数据通过计算得出了403Nb热压缩的Z参数和流变应力方程;对变形后的组织分析表明:403Nb动态再结晶以晶界弓出机制形核,在变形组织中有少量宽度为30～100nm的细小孪晶,基体中的NbC对位错有钉扎作用,提高了其热变形激活能.

关键词: 403Nb叶片钢 , 热压缩 , 热变形激活能

403Nb叶片钢热压缩变形研究

王立民 刘宁 刘正东 杨钢 张秀丽

钢铁

为403Nb叶片钢实现热连轧组织性能预报系统提供数据，采用Gleeble-3500热模拟试验机，对403Nb进行了热压缩试验。根据试验数据通过计算得出了403Nb热压缩的Z参数和流变应力方程分别为： ，σP＝14.5926ln ＋1002406.111•T－1－604.613658；对变形后的组织分析表明：403Nb动态再结晶以晶界弓出机制形核，在变形组织中有少量宽度为30~100nm的细小孪晶，基体中的NbC对位错有钉扎作用，提高了其热变形激活能。

关键词: 403Nb叶片钢;热压缩;热变形激活能

镍基单晶高温合金DD403显微偏析

高斯峰 , 刘林 , 张军 , 肖俊峰 , 张炯

材料科学与工程学报 doi:10.14136/j.cnki.issn 1673-2812.2015.06.005

采用选晶法在改进型Bridgman定向凝固炉中制备镍基单晶高温合金DD403,利用电子探针(EPMA)技术研究了DD403合金在枝晶生长条件下的显微偏析.结果表明,随着抽拉速率增加DD403的偏析程度逐渐加剧.偏析于枝晶间元素Al、Ti和枝晶干元素Co、W的偏析程度随着抽拉速率的增加而增大,而合金元素Mo和Cr的偏析比接近于1,基本不存在偏析,且偏析比随抽拉速率增加没有明显变化.研究结果同时表明,随着抽拉速率增加DD403的共晶含量逐渐增加.

关键词: 镍基单晶高温合金 , 定向凝固 , 显微偏析 , 共晶

Introduction to atmospheric corrosion research in China

Science and Technology of Advanced Materials

In this paper, we introduce the research on atmospheric corrosion in China. We describe the climate characteristics and the classification of atmospheric corrosivity across the whole country. We also describe the rusting evolution under simulated wet/dry cyclic conditions. (C) 2007 NIMS and Elsevier Ltd. All rights reserved.

关键词: atmospheric corrosion;corrosivity;rusting evolution;weathering steels;rust;mechanism;so2;o-3;no2

Recent Advances of Laser Coating Technology in China

LIANG Yong LI Ruiguo Institute of Metal Research , Academia Sinica , Shenyang 110015 , ChinaInstitute of Corrosion and Protection of Metals , Aademia Sinica , Shenyang , 110015 , China

材料科学技术（英）

Recent advances in laser coating technology including laser cladding,laser surface alloying and laser vapour deposition in China are reviewed in this paper.

关键词: laser , null , null , null , null

K403合金高性能钎焊技术研究

张胜 , 侯金保 , 郭德伦 , 张蕾

航空材料学报 doi:10.3969/j.issn.1005-5053.2006.03.077

用新型镍基钎料3P1对K403合金进行真空钎焊试验,分析钎焊接头的微观组织和连接机制,测试接头高温力学性能.结果表明:采用3P1钎料,在1230℃/10min+1160℃/4h条件下进行K403合金钎焊,可以获得无缺陷的,与基体组织相似的钎焊接头,其1000℃下高温拉伸强度可以达到基体强度的90%,高温持久强度可以达到基体强度的70%以上.

关键词: K403合金 , 3P1钎料 , 微观组织 , 力学性能